Effect of Precipitation on Hot Deformation Behavior and Processing Maps of Nickel-Base UNS N10276 Alloy

Abstract

The hot deformation characteristics and processing maps of aged nickel-base UNS N10276 alloy were investigated and compared with those of solution-treated UNS N10276 alloy at temperatures of 950–1250 °C and strain rates between 0.01 and 10 s−1. The dominant precipitated phase in the aged alloy was identified as topologically close-packed (TCP) μ phase enriched in Mo and Ni. The precipitates present in the UNS N10276 alloy could significantly facilitate flow softening after peak stress at temperatures lower than 1150 °C and strain rates higher than 0.01 s−1. Processing maps at true strains of 0.1–0.9 were developed using the dynamic materials model and experimental flow stress data. Although aging treatment slightly shrank the suitable hot working window of this alloy, the aged alloy showed higher peak efficiencies of power dissipation and smaller unstable regions in comparison with solution-treated alloy. Furthermore, aging treatment eliminated the instability region of processing maps at true strains of 0.2–0.5. The precipitated phase promoted dynamic recrystallization (DRX) by the particle-stimulated nucleation (PSN) mechanism, which resulted in the larger fraction of DRX as well as finer and more uniform grain structure in the aged alloy specimens compared to the solution-treated alloy.